The synthesis of triorganosilylated carbamates and phosphoramides bearing a nitrogen mustard functionality will be continued to provide new classes of potential CNS antitumor prodrugs. Kinetics of their hydrolytic reactivity will be measured to gauge their relative "activation" rates, i.e., desilylation leading to bis-alkylating agents. A variety of known anticancer drugs which may be converted to organosilyl derivatives will be similarly studied, and all compounds will be submitted to the National Cancer Institute for preliminary anticancer screening tests.